A8 w12 2005 noisy power steering

[paraline]

Hi, Much appreciated if forum member can advise me if it's normal for power steering pump to make whining noise?

Seems worse in winter and better in summer, but always there. had pump replace (twice!) by Audi, and technician tells me that it "works within spec".

last time they replaced pas pump, noise was reduced, but still cleary there.

Is this an inherent problem or do I just have oversensitive hearing?:Blush:

Thanks....

[Crasher]

This one for forum memebr a8 tech me thinks.

[paraline]

thanks, hopefully I'll hear from him...

[a8 tech]

I would and can tell you the level drops and draws air into the fluid which aerates and causes the noise

The pas reservoir is a bugger to get to situated beneath the front left air filter box

Now there a couple of things to consider here

1 tyre tread pattern and wear against road surface and turning speed

2 If the level is ok and pressure is ok and geometry ok then Ackerman angle affect can create the noise

3 If the level has dropped then a leak is present within the rack

4 the ribbed belt has stretched over time causing the pump to generate the noise

5 the suction pipe or return hose has a restriction

so the noise could be transmitted from the tyres or Ackerman angle and road surface

aeration of the oil due to low level

belt slippage

pressure testing the system when faulting will highlight flow and pressure

swapping the wheels from another vehicle

checking camber and tyre footprint

99% of the A8/S8 I have seen with this issue are down to natural level drop over the years and the lack of topping up at service due to the awkward access to the reservoir

or mistaken noise which was actually the air suspension compressor located nsf inner wing below the pas pump

note

larger wheels 19/18's with quattro drive will always create slow manoeuvring or static lock to lock noise as the larger footprint tyre has a greater surface area of traction and smaller turning angle

this will be feedback via pas noise and in some cases transmission noise

pas oil viscosity changes depending on ambient temp and flow so that explains the winter summer difference

also consider tyre compound or tyre tread pattern

compare with s8 or another w12 if possible

[paraline]

Thanks so much for such comprehensive reply, must admit I did not expect so many possible causes.


Will try to refine down, if you could help...?


I would and can tell you the level drops and draws air into the fluid which aerates and causes the noise



1 tyre tread pattern and wear against road surface and turning speed

>>>>>not likely, whining noise present loud and clear while car stationary

2 If the level is ok and pressure is ok and geometry ok then Ackerman angle affect can create the noise

>>> Audi watford advise levels are OK, car has new tyres and 4 wheel alignement

3 If the level has dropped then a leak is present within the rack

>>>>NO leaks

4 the ribbed belt has stretched over time causing the pump to generate the noise

>>>>>Would this make whining noise while car is stationary and wheels straight?

5 the suction pipe or return hose has a restriction

>>> Asked audi about return hose , they say it's OK. Not sure about suction pump

so the noise could be transmitted from the tyres or Ackerman angle and road surface

aeration of the oil due to low level

>>>>>>Again, whines even when stationary, most audible on cold mornings

belt slippage

>>>>>> Not sure if this was checked...


99% of the A8/S8 I have seen with this issue are down to natural level drop over the years and the lack of topping up at service due to the awkward access to the reservoir

>>>>>>>>>This can be discounted as PAS pump replaced twice in last 12 months

or mistaken noise which was actually the air suspension compressor located nsf inner wing below the pas pump

>>>> Hmmm... now this is something that makes sense to me. Whining while stationary could be compressor, but why whining increases when turning steering at low speeds?

larger wheels 19/18's with quattro drive will always create slow manoeuvring or static lock to lock noise as the larger footprint tyre has a greater surface area of traction and smaller turning angle

>>> car has 20's. no lock to lock noise, just whine

this will be feedback via pas noise and in some cases transmission noise

pas oil viscosity changes depending on ambient temp and flow so that explains the winter summer difference

>>>>>>>>yes, understood

also consider tyre compound or tyre tread pattern

>>>>>Changed from pirelli to michelin, no difference

compare with s8 or another w12 if possible

>>> not really

Thanks again for very detailed explanation. Hope above comments narrow it down somewhat.

Much appreciate your assistance, have been battling with Audi watford for 16 month on this....:aargh4:

[a8 tech]

If the noise is present without being loaded at idle then it would make sense for the dealer to disconnect the pas ribbed belt to eliminate engine noise or consequential noise from another part to localise the fault

If the noise is only present with pas belt connected then it leaves only the effect of belt tension or there is a pressure problem/flow

This would then suggest that the dealer uses a pressure gauge and also chassis ears to asses the pressure and listen to individual components on the system via the chassis ears to localise the noise

However I strongly recommend the dealer compares with another vehicle so you can clearly see between yourself if the noise differs over the two vehicles

I maintain 4 w12's so I understand there not to great in numbers

There is the option for you to seek out a w12 and check yourself and if possible record your findings to present to the dealer

Good luck and hopefully I have provided the information to resolve your concern

Regards

Jon

[paraline]

Hi Jon,

many thanks again for advised course of action.

From your experience with W12's you maintain, is there an issue with whining pas ?

I also wonder which area you are at, perhaps you could fix this ( I am near watford/M25)

Thanks
Dan

[a8 tech]

They all whine on stationary full lock but because the w12 lump is so quite you can hear it lol

It would be my advise to double check the level as they tend to drop after filling when a repair has been under taken and in most cases its best to leave 24 hours after repair to check the level as it only needs to drop below minimum slightly to allow air to be sucked in especially when the pas is loaded up.

I'm based in the Northwest

[paraline]

thanks. will check levels again. I know whine is likely on full lock, but can't believe it should be heard when stationary with wheels straignt. Shame we do not live closer to each other...